In their study of the effect of photodynamism on insects, the present investigators have made considerable progress toward a determination of mode of action and practical application for insect control. At this critical point in the investigation, four major areas will be emphasized. (1) The effects of sublethal dye-light dosages will be determined for the house fly adults and larvae including developmental abnormalities, fecundity and egg viability. (2) Further studies on mode of action will be conducted including the following: photodynamic effect on hemocytes, electrophoretic analyses of hemolymph proteins, electrophysiological effects on muscle and nerve resting potential and effects of various levels of Na/K which are related to water balance in insects. (3) Field studies to determine the efficacy of photodynamism for insect control will include use of dyebait stations equipped with light sources of appropriate wavelengths and intensities and utilizing various dyes and concentrations. (4) Rats will be studied to determine the effects of dyes (especially Food and Drug Administration dye additives) and light following topical and oral dye treatments.